Fluorescent protein biosensors have grown into one of the most powerful tools for the study of cell biology. When combined with intravital microscopy, these biosensors have the potential to sensitively interrogate molecular, physiological and physical events occurring within living cells In the most relevant, in vivo setting. However, the utility of fluorescent protein biosensors for in vivo study has been limited by the difficulty of in vivo gene delivery, largely restricting their application to studies of cells in, or derived from transgenic animals, in order to realize the potential of fluorescent biosensors for studying cell biology in vivo, flexible methods of in vivo gene delivery must be developed. The goal of the Probe Delivery Core is to develop and characterize simple, inexpensive and effective methods for expressing fluorescent biosensors In the rodent kidney and to provide these methods to end-user investigators in the form of fully characterized probes and detailed protocols for the use of these probes and for the development of new probes. These probes will provide renal researchers with powerful new tools that will enable them to conduct novel intravital microscopy studies addressing fundamental issues of renal physiology, cell biology and pathophysiology.